Recently, vehicles are manufactured based on studies conducted to secure driving force using internal combustion engines and/or electric motors, in order to reduce air pollution from exhaust gas of vehicles. Accordingly, the vehicles have evolved in the order of hybrid vehicles, plug-in hybrid vehicles and electric vehicles. In this case, the hybrid vehicles and plug-in hybrid vehicles have an internal combustion engine, an electric motor and a battery pack, and the electric vehicles have an electric motor and a battery pack, but not an internal combustion engine.
Accordingly, the battery pack has evolved together with hybrid vehicles, plug-in hybrid vehicles and electric vehicles. The battery pack is configured to be charged externally from the electric vehicles. The battery pack has a pack case and a battery module, and the pack case comprises a lower case and an upper case, thereby encasing the battery module. The battery module has battery cells and cartridges between end plates. In this case, movement of the battery module is restricted inside the pack case by an inner shape of the lower case or the upper case.
However, the inner shape fills inner space of the pack case at a side portion of the battery module, and thus prevents vibration of a component during and after an assembly operation of the battery pack in the lower case or the upper case, but has a structure that is vulnerable to the vibration of the component between the lower case and the upper case. Further, when having a shallow accommodating depth of the battery module in the lower case or the upper case, the inner shape cannot prevent deviation of the component from the lower case or the upper case during an assembly operation.
Therefore, numerous studies for preventing vibration of a component and/or deviation of the component during and after an assembly operation of the battery pack are being conducted. One example of the above studies is disclosed in ‘BATTERY PACK HAVING A COMPACT STRUCTURE’ of Japanese Patent Application No. 2013-534360 (Laid-open on Sep. 2, 2013). The battery pack has a pack case, a battery module and a pack cover. The pack case accommodates the battery module, and the pack cover covers the battery module on the pack case. Here, the battery module has a lower end plate, a cell module stack and an upper end plate that are stacked sequentially.
The upper end plate has fixated extension members at edges, and the fixated extension members are screw-coupled to the pack cover through screw members. Therefore, the screw-coupling of the fixated extension members and the pack cover enables prevention of vibration of a component during an assembly operation of the battery pack in the pack case or the pack cover and between the pack case and the pack cover. However, the assembly operation of the battery pack requires repeated screw-coupling of the fixated extension members and the pack cover, and thus needs a lot of work hours of operators.